[PATCH] powerpc: Fix bug in bug fix for bug in lmb_alloc()

My patch (d7a5b2ffa1352f0310630934a56aecbdfb617b72) to always panic if
lmb_alloc() fails is broken because it checks alloc < 0, but should be
checking alloc == 0.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/mm/lmb.c

@@ -232,7 +232,7 @@ unsigned long __init lmb_alloc_base(unsigned long size, unsigned long align,
 
 	alloc = __lmb_alloc_base(size, align, max_addr);
 
-	if (alloc < 0)
+	if (alloc == 0)
 		panic("ERROR: Failed to allocate 0x%lx bytes below 0x%lx.\n",
 				size, max_addr);